Fitness | KATHY SMITH

Heart Rate Monitor Can't Be Beat for Boosting a Workout

For years I used to see joggers and cyclists measure their pulse every few minutes--something I never felt the need to do. Nowadays I'm just as likely to see aerobic exercisers, both at the gym and on the street, with heart rate monitors strapped on to their wrists and chests. Until recently, I thought that these were just expensive exercise toys.

Then, to improve my endurance while training for a recent 10K, I started working with Amy Nelson, who runs Heart Aerobics, a heart-rate training workshop. It was she who insisted that I get myself a monitor, calling it a "necessary tool for improving fitness."

The more I learn about the monitors, the more I agree with her. Here's why:

The harder you exercise, the more oxygen your body demands, and the more out of breath you get. And if you work harder still, you'll hardly be able to catch your breath at all. Which means that you're pushing your muscles past your system's ability to deliver oxygen to the parts screaming for it. Still, until the next day, when you feel so sore you can barely walk, you think you've really had a great workout. You stand in front of the mirror, believing that you can almost see the fat burned away. Wrong.

*

Working anaerobically as opposed to aerobically--that is, making your heart beat faster than the body's ability to supply oxygen--is counterproductive to the goal of losing fat. While aerobic workouts are primarily fueled by the fat in your body, anaerobic workouts force your body to find fuel in its stores of carbohydrates, which are more readily converted to energy. In addition, anaerobic workouts cause waste products in the muscles to build up. That not only tires you faster, but also makes you hurt all over.

In short, you're working too hard--an extremely common problem that explains why you keep exercising and still don't have the body you want. Frustrated by that obvious fact, you may want to give up entirely. Either that, or you'll keep pushing yourself harder and harder, which sets you up for more injuries, infections (due to a compromised immune system) and burnout.

Less common but still epidemic is the problem of working too lightly. Some people do the same workout every single time, never adjusting for the increase in their body's efficiency. So the workout that once exhausted them and taxed their systems is now just a matter of routine; their hearts barely notice the difference. So although they put the time in, they never improve either their fat or fitness level.

But to what level are you supposed to raise your heart rate during exercise? That's the question that the heart rate monitor answers by automatically letting you know when you're working within a prescribed range of maximum efficiency. With the monitor, you're the one in control. You become your own trainer or coach.

*

Here's how to start: Using the monitor, determine your aerobic threshold, which is the highest level of workout intensity you can sustain while still feeling comfortable. Then determine your anaerobic threshold, which is the level past which your workout feels unsustainable. The process of defining both levels will take some amount of experimentation, over a period of days; no chart or graph can define it for you.

*

Once you know those levels and can set your monitor accordingly, take your total training time and divide it into threes: easy, moderate and hard. Do one easy workout (below your aerobic threshold) for every hard workout (anaerobic), and twice as many moderate workouts (at your aerobic threshold). So let's say you work out four times a week. That makes one easy, one hard and two moderate workouts. You do this because training at different intensities is what causes the body to adapt and improve its fitness level.

What surprised me, when I began using the heart rate monitor, was how the exact same exercise routine could produce such wildly different heart rates from day to day. On the morning after a good night's sleep, for example, it might take some real effort to reach my aerobic threshold. But that same effort expended in hot, humid weather, or when I'm stressed out, feeling poorly or just off a plane would send me quickly into my anaerobic zone. So while I was putting in the same amount of time, I wasn't necessarily getting the results I wanted, because I didn't know what my heart was doing. Believe me, this was a revelation.

Amy was right. Heart rate monitors really are indispensable. Using one, you're bound to see the difference, both in your fitness level and the way you look. When it comes to smart exercise, this is one of the right tools.

*

Copyright 1999 by Kathy Smith

Kathy Smith's fitness column appears weekly in Health. Reader questions are welcome and can be sent to Kathy Smith, Health, Los Angeles Times, Times Mirror Square, Los Angeles, CA 90053. If your question is selected, you will receive a free copy of her new video, "Kickboxing Workout." Please include your name, address and a daytime phone number with your question.